This invention relates to improvements in solar energy panels of the type adapted to be mounted on a roof or the like to absorb solar energy and convert it to heat which is conducted to a fluid medium such as water and then utilized in the heating system for the building or for the storage of hot water for any desired purpose.
In recent years, the rapidly increasing costs of energy derived from fossil fuels have resulted in numerous proposals for the use of alternate energy sources, such as solar energy. There have been numerous suggested constructions for solar energy collectors which may be mounted on the roof of a house to provide energy for domestic hot water or space heating. While some of the prior collectors have met with limited success, one of the primary obstacles still presented to the use of roof mounted solar energy collectors is that they are relatively expensive, not only in their manufacture but also in their transportation, handling and installation. The roof mounted collectors are exposed to the elements at all times which heretofore has required the use of expensive materials and construction. Moreover, the thermal efficiency of most leaves much to be desired. The combined effect of these difficulties is that solar collector installations generally require a very substantial initial financial committment and require a long period of time in order to begin to recapture the initial investment. Typically, prior efforts to develop low cost solar collectors are believed to have resulted in units having relatively poor efficiency.
In brief, the present invention includes a rectangular frame which defines the panel. An absorber plate having water tubes, is secured in the frame with its blackened, energy-absorbing surface facing upward. Water inlet and outlet means are provided to communicate the tubes with the water circulation system. Secured to the frame, and extending above the absorber plate are a pair of spaced glazings, including an inner glazing and an outer glazing. Both glazings are formed from transparent plastic films, as will be described. The inner glazing is secured to the frame to define an air space between the copper absorber plate and the inner glazing. The inner glazing is formed from a plastic film material which is not adversely affected by the high temperatures which may develop within the air space, as a result of what is sometimes characterized as the "greenhouse effect". The outermost film is heat shrinkable and is shrunk to draw it tightly over the frame, above the first glazing, to define a second air space. The outer glazing is a tough plastic skin and can withstand adverse weather conditions such as hail, snow loads and the like. The outer glazing surrounds the frame to encase it entirely. Insulation is provided within the frame beneath the absorber plate. The doubly glazed frame rests on a lower sheet of insulative material which itself is enveloped in a sheet of plastic film. The juncture of the outer glazing and the envelope about the bottom insulative sheet is continuously bonded by adhesive to completely encase the collector within a tough, protective plastic film.
It is among the general objects of the invention to provide an improved solar collector panel which is of low cost and light-weight construction.
Another object of the invention is to provide a solar collector panel in which the entire panel is encased in a protective sheet of plastic material.
A further object of the invention is to provide a double glazed solar energy collector which displays improved efficiency in that it allows more of the sun's energy to reach the absorber plate than with prior double glazed systems.